A large variety of switches that are operated by a user's foot are found in the prior art. Such switches are desirable when the user's hands are otherwise occupied. For example, foot switches are often used to trigger the delivery of laser energy in a medical laser system. Typically, the doctor will be using his hands to position the patient and the laser delivery system in the proper location. At the desired moment, the doctor will press down on the pedal of the foot switch to deliver the laser energy to the treatment site.
One type of prior art medical laser is described in copending application Ser. No. 654,834, filed Feb. 13, 1991 and incorporated herein by reference. The laser described in the latter application is a solid state, flash lamp pumped, Holmium:YAG laser. This laser is marketed by the assignee under the trademark TwoPointOne.
In operating the TwoPointOne laser at higher pulsed powers, it was found that during the first pulses of the flashlamp, instabilities in the thermal parameters of the rod-shaped gain medium led to deterioration of optical elements in the laser. As described in the latter application, the problem was overcome by preconditioning the laser rod to avoid the instabilities. The rod is preconditioned by initially operating the flashlamp at a energy below the threshold for laser oscillation. In this manner, the rod is allowed to come to thermal equilibrium prior to the generation of the laser beam.
The laser described above is typically actuated by a foot switch. At present, when the doctor presses on the foot switch, the laser will first enter the preconditioning mode during which time the rod is brought into thermal equilibrium. This process takes about one second. As soon as the rod has been preconditioned, the energy to the flashlamp is automatically increased above threshold and a laser beam is generated and delivered.
While this approach has improved the stability and lifetime of the system, a delay has been created between the actuation of the foot switch and the delivery of the laser energy. From the standpoint of the doctor, it would be desirable to eliminate that delay. The subject foot switch has been developed to overcome this problem.
The subject foot switch can be used in other medical laser systems. For example, the assignee herein manufactures and sells a line of ophthalmic medical lasers including the Novus 2000. This system includes a slit lamp through which the ophthalmologist looks to examine the eye of the patient. When the doctor begins to treat the eye with the laser beam, an eye safety filter is dropped into place within the slit lamp to protect the doctor's eye from reflected laser radiation. The safety filter is typically a coated optical element that allows a certain fraction of visible light to pass but substantially blocks radiation at the wavelength of the treatment laser beam.
Because of the reduced transmission of the filter, it is important that the filter be outside of the visual path of the slit lamp while the doctor is examining the patient's eye and aligning the aiming beam of the system just prior to treatment. However, the eye safety filter must be moved into place prior to delivery of the treatment beam. The movement of this filter is not silent and is typically accompanied by a clicking sound immediately followed by a pulse of laser energy. Thus, the patient hears the click made by the movement of the filter and then is hit with the laser beam which causes a certain degree of pain. It has been found that in a short time, the patient will begin to flinch upon hearing the clicking sound of the safety filter moving into place. When the patient flinches, the ability to accurately deliver the treatment beam is diminished.
As can be appreciated, it would be desirable to disassociate the sound of the filter being moved into place from the delivery of the treatment beam. The dual actuation foot switch of the subject invention addresses that need.
Accordingly, it is an object of the subject invention to provide a new and improved dual actuation foot switch.
It is a further object of the subject invention to provide a dual actuation foot switch for use with medical laser systems.
It is still another object of the subject invention to provide a foot switch that can independently initiate the warm-up stage of a laser and subsequently initiate the generation of laser energy.
It is still a further object of the subject invention to provide a foot switch that can independently actuate the movement of a safety filter and subsequently initiate the delivery of laser energy.